Predicting Weather

-Introduction
-How far can Meteorologists accurately Predict the Weather?
-Computers
-Radars

The most straightforward way to predict the weather is to simply look out the window.

William Bonner, an authority on forecasting with the University Corporation for Atmospheric Research in Boulder, Colo, once said, 'If the visibility is 15miles and there is not a cloud in the sky, you can bet it's not going to rain in the next 30minutes.'

'But if just over the horizon, 45miles away, there's a squall line moving along at 40mph, one hour from now you can get a lot of rain'

However, for more accurate weather forecasts, you need something more than your eyes. New observational tools like radars, satellites, together with specially designed computers can give a clearer picture to the ever-changing weather conditions for better forecasting results.

How far can Meteorologists accurately Predict the Weather?

Weather has always been a significant concern to humankind, and our inability to control it has led us down through the ages to try to measure it, compare it to previous years, and predict it. Prediction, however, requires a lot of information about conditions in different locations as well as a way to convey that information between distant places. In the latter half of the nineteenth century, the telegraph made it possible for meteorological data from stations scattered over a huge area to be collected rapidly, leading to the creation of several national weather services. The global observational network grew in sophistication during the twentieth century, especially after launch of the first satellite in 1957.

Today, satellites, commercial airlines, and ships at sea take measurements. Information also comes from balloons that are released twice a day into the upper atmosphere by meteorological stations around the globe, as well as by fixed buoys that record temperature several hundred meters deep in the ocean.

Even with all this high-tech help-including sophisticated computer models--we can predict the weather with reasonable accuracy only a few days in advance. Accurate weather predictions require great skill and experience. Till this moment, no one can predict the detailed, day-by-day weather more than a week ahead. In fact, forecasting skill generally drops off quickly after three or four days.

For more than seven days ahead, the best forecasters can do now is offer odds of the weather being average or some comparison to average-hotter, colder, drier or wetter than average for a period such as a week, a month or a season. These forecasts do not try to say what each particular day will be like.

Scientists have good reason to believe that despite improvements in observations, computers and computer models, detailed forecasts for much more than two weeks ahead never will be possible.

Computers

Computers become an important role of weather forecasting in the world today.

Let's see how they help in the process.

1. Quality Control-

correct errors of gathered information and ensure reports make sense

2. Analysis-

use data to draw separate weather maps for the seven levels of the atmosphere used in forecasting

3. Input-

using the maps drawn, figure out the weather in each of the seven-layer grid

4. Processing-

do all kinds of calculation and keep track of the changing weather condition

5. Output-

draw various kinds of weather maps using the collected and analyzed data, and produce weather forecasts

Radars

The word "radar" is an acronym for "RADio Detection And Ranging".

Since World War ¢º radar has been helping track weather. All weather radars detect the location of storms, track them and give data on strength.

The latest radars, using the Doppler principle, also detect wind speeds and directions and can often "see" winds outside of storms. the Weather Service will make Doppler pictures available to television stations as Doppler radars are installed around the country.

How Radar works

1. Radar antenna sends out pulses of radio waves.

2. Raindrops, other kinds of precipitation and even dust, insects or boundaries created by air-temperature contrasts reflect some radio waves to the antenna.

3. The radar's electronic circuits convert the returning radio waves into maps and other displays. The new Doppler radars use computers to create displays from faint radio waves, such as from air boundaries.Conventional radars couldn't do this.

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